JSDoc @template should introduce a type in JS

[ghost]

TypeScript Version: nightly (2.4.0-dev.20170609)

Code

a.js

/** @template T */
class C {
    /** @param {T} x */
    constructor(x) {
        /** @type {T} */
        this.x = x;
    }
}

Expected behavior:

No error.

Actual behavior:

app/main.js(3,17): error TS2304: Cannot find name 'T'.
app/main.js(4,17): error TS7006: Parameter 'x' implicitly has an 'any' type.
app/main.js(5,20): error TS2304: Cannot find name 'T'.

[dyst5422]

#16485 is related

[mhegazy]

duplicate of #18135